Myanmar was accused of the systematic ethnic cleansing of Muslim Rohingyas on Monday as Human Rights Watch reported evidence of mass, unmarked graves in western Rakhine State following deadly riots between Buddhists and Muslims there last year.

The findings of the report, entitled ‘All You Can Do is Pray,’ represent “the most sustained and systematic” rights abuses in Myanmar since the start of a much lauded reform process more than two years ago, said Human Rights Watch (HRW) Deputy Asia Director Phil Robertson.

“The government needs to put an immediate stop to the abuses and hold the perpetrators accountable or it will be responsible for further violence against ethnic and religious minorities in the country,” he said.

HRW reported the first evidence of four mass, unmarked graves in the area – including bodies with arms tethered with plastic and rope – amid fears there could be more such sites in the area which remains under martial law.

In Mrauk-U Township, home of a large collection of 15th century Buddhist and Islamic temples, witnesses claimed police and army officials ordered villagers to dig mass graves to save time after at least 52 Rohingyas were killed in a single day.

“The responsibility for these deaths falls squarely on the government,” said Robertson.

The army, riot police, a border guard force and regular police officers were responsible for turning a blind eye and in some cases taking part in abuses during two violent episodes in Rakhine State in June and October last year, which led to more than 200 dead and 270 injured, according to official figures. HRW said the actual numbers are likely to be higher.

More than 125,000 Rohingya and other Muslims were displaced during the rioting and many are still unable to return home with thousands of people confined to ghettos. There remain almost no Rohingyas in Sittwe, the provincial capital, said HRW.

Leading Buddhist monks in Rakhine State and elsewhere in Myanmar have been accused of inflaming tensions in the area. HRW said there were numerous cases in which monasteries had organized anti-Rohingya campaigns which they themselves described as “ethnic cleansing.”

“There are different factions within the Buddhist Sangha (Budhhist monastic community),” said Robertson, adding that some Buddhists have been critical of anti-Muslim activities.

“It is completely not true that the Buddhist monks and security forces were involved in killings,” he said. “The monks, who are the sons of Buddha, have to strictly follow the basic moral code when it comes to taking lives – they are not supposed to do that even mentally.”

In response, Wunna Shwe, co-secretary of the Islam Council of Myanmar, described last year’s events in Rakhine State as “pure acts of anarchy.”

“[They occurred] due to the lack of law enforcement by the authorities concerned,” he added.

Government spokesman Ye Htut was not available for comment on Monday.

A government sponsored commission of inquiry is expected to release its own findings of what happened during last year’s rioting in Arakan State on Tuesday.

Two representatives of the Islam Council were originally included on the commission but were later removed without explanation, said Wunna Shwe.

President Thein Sein, who was expected to read the findings on Monday, was also the same day due to receive the International Crisis Group’s top peace award in New York for his government’s recent reforms.

Also on Monday, the European Union was expected to announce the full removal of sanctions on Myanmar with the exception of arms trading.

“It’s a premature lifting of sanctions,” said Robertson. “At the end of the day, it makes the EU look bad.”